1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly to a dual-purpose transmission circuit capable of receiving two or more signals or voltages, or a signal and a voltage, through a common input pad, and an input method using the same.
2. Description of the Related Art
In general, a semiconductor device has multiple pads for various purposes. For example, some types of pads are a data input pad for receiving data from outside of a semiconductor chip, a data output pad for outputting data from inside of a semiconductor chip, address pads for receiving an address signal from outside of a semiconductor chip, a voltage input pad for applying a predetermined voltage from the outside and a control signal pad for receiving multiple control signals to drive the semiconductor device.
Recently, the number of required pads in a semiconductor device has increased, as higher integration density and more functions are required. Also, the power voltage and ground voltage must be kept constant in a semiconductor device. However, if the load on a voltage line is great, as in a large integrated semiconductor device, it is very difficult to keep a constant voltage during the operation of the device. In order to solve the above problems, a plurality of voltage apply pads may be placed within the semiconductor device. However, the number of pads is limited, because a semiconductor device tends to be miniaturized.